Absolute permissive automatic block-signal system.



UNITED STATES PATENT curios.

WILMER W. SALMON, OF NEW ROCHELLE, AND FRANK L. DODGSON, OF ROCHESTER.

NEW YORK, ASSIGNORS TO GENERAL RAILWAY SIGNAL COMPANY, OF GATES, NEW YORK, A CORPORATION OF NEW YORK.

ABSOLUTE PERMISSIVE AUTOMATIC BLOCK-SIGNAL SYSTEM.

Specification of Letters Patent.

Original application filed February 7, 1911, Serial No, 607,098. Divided and this application filed December 27, 1915, Serial No. 68,786. Renewed April 15, 1918. Serial No. 228,807.

T 0 all whom it ma 1 concern Be it known that we, \VILMER W. SALMON and FRANK L. Donosox, citizens of the United States, and residents of New Rochelle and the city of Rochester, in the county of Monroe and State of New York, have invented a new and useful Absolute Permissive Automatic Block-Signal System, of which the following is a specification.

This invention relates to automatic block signal systems and is especially adapted for use on single track railways. The object of the invention is to provide a signaling system adapted to be operated by the ordinary closed track circuits commonly used in automatic block signaling systems and adapted to secure head-on protection from passing siding to passing siding, with blocks for following train moves as short as track conditions require.

- So far as known to us prior to our invention, a greater part, if not all of the single track railroads in use have employed the ordinary automatic block signal system in which a t 'ain entering the block from either direction gives the same indication and thus has the same protection for following trains as for head-on trains. Many attempts have been made to attain the results attained by our invention, but, so far as known to us, iione of the systems proposed were adapted to be operated by the ordinary closed track circuits in common so on railways, and all of them involved using additional and complicated apparatus or circuits, and making the operation of the signals for following movements more or less dependent upon the operation of signals governing head-on movements.

Primarily. the invention may be termed a unit system in that our means are adapted to be located at and operated by any track circuit controlling a signal governing traffic in one direction without regard to signals governing the traflic in the opposite direction; but it will be understood, of course, that in the practical embodiment of our invention, the usual signals governing headon protection are employed.

In carrying out. our invention, we preferably employ a signalcircuit adapted to be opened by a train on the track circuit sections of a block and a further signal circuit- 'we have selected as an example for the purpose of explaining the principles 1nvolved, it being understood that the invention may be embodied in various forms and arrangements of apparatus.

In the accompanying drawings. the figure 'illustratesdiagrammatically the circuits and apparatus of one embodiment of our invention applied to a railway.

"onst'ruction.Referring to the drawin 1, 2 and designate track circuit sections, separated by means of insulating joints 4; 1 9. and 3 designate track batteries for creating a difference of potential. between the two rails of the track; 1 2 and 3 (les ignate relay coils normally energized by current flowing therethrough due to the difference of potential created by the track batteries; 1 designates a relay armature held normally in the upper position 'as shown by reason of the current flowing in relay coil 1 2 2* and 2 likewise designate armatures normally in the upper position shown by reason of current in relay coil 2 3 likewise designates the armature of relay coil 3 normally held in the upper position; 5 designates a semaphore as does likewise G; 5 and 6 designate the electric motors for moving semaphores 5 and 6 respectively; 5 and 6 designate the liold clear devices for holding the semaphores 5 and 6 respectively in their moved position; 5 and 5 designate metallic arms moved in unison with semaphore 5 and designed to at times make contact with metallic strips 5", 5 5 and 5, the arm 5 making contact with metallic strip 5 at the 45 position of the semaphore and for a few degrees on either side of such 45 position, the arm 5* making contact with metallic strip 5 at the zero or danger position of the semaphore and during the whole movement of the semaphore except be last few degrees; the armii making contact with the metallic strip 5 at the full clear or 90 position of the semaphore 5 and for a few degrees on either side of such 90 position,

the arm 5 making contact with the metallic strip 6 at the zero or danger position of the semaphore and during the whole movement of the semaphore except the last few degrees, 6 not making contact at the zero or danger position of the semaphore with metallic strip 6 but making contact therewith as soon as the semaphore has moved a few degrees and remaining in contact therewith during the whole of the remainder of the movement of the semaphore; 8 designates a relay coil which when current passes there through causes armature 8 to be held in its upper position; 7 designates a relay coil which when acurrent of sufiicient value passes therethrough will draw armature 7 to the upper limit of its movement; 9 designates a resistance which is of such value that it will allow sufficient current to pass therethrough to sufliciently energize coil 7 so that it will hold armature 7 in its upper position if already there but will not allow sufficient current to pass therethrough to sufiiciently energize coil 7 so that it will move armature 7 to its upper position, if it is in its lower position;

O7)erat z'0n.In the normal condition of the connections, relay'8 is'energized by'cur rent in the following circuit: positive terminal of battery 17, wire 19, relay armature 3 wire 20,relay armature 2 wire 21, relay coil 8, wires 22, 23, 24 and 25 to the'negative terminal of battery 17; the relay coil being thus energized the armature 8 is normally held in its upper position.

If a train moving in the direction of the arrow a comes upon section 1, it willshunt the relay 1 thereby dropping Tthearmature 1 so that it makes connectionwith its back contact, thereby establishin the following circuit: positive terminal of "attery 10, wires 26 and 27, armature 8, wire's 28 and 29, metallic strip 6", arm 6, wire 30, motor 6, wires 31, 32 and 33, relay armature 1, wires 34 and 24 to the negative terminal of battery 10. The current flowilng 'i'n such path will cause the motor to operate to move the semaphore '6 to the 45f or'cilear position causing the aim -;to"fmove overfij meta-llic strip 6 mutate semaphore almost reaches the 45 position; when arm 6 will break contact with strip '6 thus stopping the motor,

but at the 45 position of the semaphore 6 the arm 6 will make contact with metallic strip 6 so that the current which formerly flowed through the motor will now flow through the holdelear device from the wire 28 by the, following path: wire 28, wire 35, strip 6, arm 6, wire 36, holding coil 6 wire 37 to wire 33 and so by the before quently pgrmits the semaphore 6 to fall to the zero or danger position to protect the train. The semaphore 6 will remain at danger and cannot be moved to the 45 position so long as a train is on slction 2 or 3 for under such conditions the energizing circuit for relay coil 8 is broken either by the dropping of armature 2 or armature 3 de pending on whether a train is on section 2 0r 3. As soon, however, as the train which 'passed signal 6 passes the end of track section 3 the relay 8 will again become energized, relay armature 8 will belifted and the system would then be in condition to be again operated as before.

When a train enters section 2 traveling in the direction of the arrow at the semaphore 6 is, at that instant, in the 45 or clear position so that arm 6 makes contact with strip 6 and as by the entrance of the train on section 2 the armatures 8 and 2 are allowed to fall for reasons heretofore explained, a circuit is formed as follows: positive terminal of battery 10, wires 26, 44 and 38, arm 6 strip 6 wire 39, armature 2-", wires 40 and 41, relay coil 7, wires 42, 23 and 24 to the negative terminal of battery 10. The current flowing in the above mentioned circuit sufliciently energizes coil 7, so that it lifts armature- 7, thereby rendering efiective another circuit as follows: positive terminal of battery 10, wires- 26 and 27, armature 8, wire 43, resistance 9, wire 41, relay coil 7, wires 42, 23 and 24 to the negative terminal of the battery. The current flowing in this last traced circuit it will be observed does not depend upon the position of semaphore 6 for its continuity, but due to the resistance 9 of the current flowing is only'suflicient to hold the armature 7 in its upper position, but is not suflicient to raise the armature if it is down, it being necessary to have a circuit made through arm 6 and strip 6 to cause suflicient current to flow through relay coil 7 to raise armature 7, so that after 7 has once been raised by the en armature 7 was still in its upper position,

upon entering section 1, it would shunt relay coil 1 and cause armature 1 to drop thus closing the following circuit: positive terminal of battery 10, wires26, 44 and! 45, armature 7 wire 46, strifi5, arm 5,"" y"vire 47, motor 5 wires 48, 49, 50, 32 and 33, armature 1 wires 3% and 24 to the negative terminal of battery 10. The current in said circuit would operate the motor 5 to move the semaphore 5 to the 45 position at which point arm 5* would break contact with strip 5 thus cutting off the-current from the motor, but at the same time the current which was flowing through the motor would be directed through the hold clear device 5 flowing from wire 46 to wire 51, strip 5, arm 5 wire 52, holding coil 5 wire 53 to wire 50 and t0 the negative terminal of the battery as before, thus holding the semaphore in its 45 position. It is to be observed that the said second train would not be able to clear semaphore 6 if a train were in either sections 2 or 3 for the very presence of a train on either of said sections deenergizes relay 8, thus causing armature 8 to be in its lower position, thus breaking the operating circuit for semaphore 6.

\Vhen the second train passes semaphore 5 it goes to the zero or danger position due to the fact that armaturel is drawn to its upper position, but all other parts of the system remain as before so that a third train approaching in the direction of arrow at wouldbe able to operate semaphore 5 to its 45 position and so enter section 2. It will be thus seen that sections 2 and 3 could be filled with trains all going in one direction; but a train approaching section 2 in the direction of arrow a could not operate semaphore 6 until the last train had left section 3, for

just so long aS there is a train on section 2 or 3 relay armature 8 would be down,

thus preventing the operation of semaphore 6. Y

It is also to be observed that as soon as the last train left section 3, the next train approaching in the direction of arrow (1 would not be able to operate the semaphore ,5 for by the exit of the preceding train from section 3 relay coil 8 would be energized and armature 8 lifted breaking circuit through coil 7 which would cause armature 7 to drop preventing the operating circuit of semaphore 5 from being closed by the entrance of a train on section 1.

If a train should enter section 3 traveling in the direction of arrow 6 it would prevent all operationof the signals 5 and 6 by the subsequent entrance of a train on section 1 moving in the direction of arrow a, for the first said train would shunt re lay 3 thus causing armature 3 to drop and break the energizing circuit of relay 8, which would cause armature h to fall and prevent the clearing of semaphore 6 when the said subsequent train entered section 1. The dropping of relay armature 8 would not however cause relay 7 to be energized by the circuit heretofore described for resistance 9 would not allow sufficient current to flow through relay coil 7 to energize it sufficiently to lift armature 7 consequently the operating circuit of semaphore 5 would be broken; which condition would exist as long as the first said train remained on sections '2 or 3.

Those skilled in the art of railway signaling and especially single track automatic block signaling can readily understand that thesystem above described accomplishes a result not before attained but long sought, for by its use all of the advantages of a signal system employing track circuits are preserved, the advantages of an automatic system are preserved and at the same time the added result of being able to govern semaphores 5 and 6 in accordance with the presence and direction of movement of a train on a track circuit section is attained.

The semaphore 5 is caused to have different aspects according to whether a train which has passed semaphore 5 going in the direction of arrow a is in section2 or section 3. This is accomplished by giving to semaphore 5 three positions so that when a train is on section 2, semaphore 5 could be moved to the 5 position, but when the train is on section 3 it could be moved to the 90 position.

A train. approaching semaphore 5 and 6 from the direction of the arrow (1 will first enter upon section 1; and if no train is on sections 2 or 3 semaphore 6 will .be moved to the i5 position allowing the train to proceed at full speed past the sig' nal and. if a train was on either sections 2 or 3 and had entered upon sections 2 or 8 from the direction of the arrow 5, the train approaching from the direct-ion of the arrow a would receive no proceed signal at all. If, however, a train approached in the direction of arrow a while a preceding train was on section the semaphore arm 6 would not be. moved but the semaphore arm 5 would move to the 5 position. In order to differentiate the condition of the presence of a train in section 2 from that when a train is in section 3, the semaphore 5 would move to the 90 position if a train approached in the, direction of the arrow or while a preceding train was on section 3, the circuit for such a movement when relay armature 7 is in its upper position due to the passing of a train in the direction of arrow a beyond the semaphores 5 and 6 being as follows: positive side of battery 10, wires 26, 44:, 45, armature 7 wires 46, 71, armature 2*, wires 74 and 75, metallic strip 5*, arm 5*, wire 47, motor 5 wires 48, i9, 50, 3'2, 33, armature 1", wires 34: and 24 to the negative terminal of the battery 10. The current flowing in the above traced path would cause the motor tooperate and move the semaphore 5 to its 90 position, it, of course, being moved previously by the same circuit hereinbefore described to the 45 position and after it has been moved by current in this last traced path to the 90 position, the current would then pass by wire 76 to metallic strip 5 arm 5 and wire 52 to the hold clear coil 5 and thence to the negative terminal of the battery by wire 53 as in the case when the motor was being operated ,It will thus be understood that a train approaching semaphores 5 and 6 in the direction of thearrow av will be given a distinctive aspect due to the presence of a train on either sections 2 or 3. V

Although applicants have selected the well known normal danger system of operating signals in connection with the embodiment of their invention which they have selected to illustrate the principle of their invention, it is to be distinctly understood that it is immaterial whether the so-called normal danger system of signaling is employed in-connection with this invention or 'whether the so-called normal clear system is employed for, to transpose from the nor mal danger system to the normal clear system would simply mean the absence of the preliminary clearing section 1, shown in each of the figures and in place thereof, the substitution of the conductor shown by dotted line 77. It is furthermore to be observed that the aspects of the signals would either with the normal danger or the normal clear systems be identical and that under the same conditions as regards the presence of a train which has passed the semaphoresii and 6, the aspects of the signal displayed to an approaching train would in the two systems be identical.

In practice the system shown would be duplicated for single track, the opposing semaphores corresponding to semaphores 5 and 6 being in the well known manner interlocked electrically, that is, 5 and 6 at one end of the block with 5 and 6 at the other end and all would be controlled by the same track circuit sections. so that a train approaching a semaphore in either direction would, if semaphore 6 moved to the clear position, enter the block controlled thereby at full speed. If the arm 5 moved to the 45 position, the train would enter the block under control. If neither semaphore assumed the 45 position the approaching train would not enter the block.

Although we have herein shown and dc scribed the relay 7 as governing a semaphore 5 it is to be understood that such are only single instances of an exhibition of its functions. In its broadest aspect the principle of relay 7 may be employed in controlling one or more aspects of any semaphore, located at any point, having a plurality of aspects, when such semaphore should have some one or more of its aspects controlled by the presence and direction of movement of a train on the track circuit sections controlling relay 7 and it is immaterial whether or not such semaphore is also jointly controlled in its aspects by other means, and therefore we desire it to be understood that such applications being well within the skill of those learned in the art of railway signaling would embody the principle of the idea of means herein set forth.

Having particularly described the construction and operation of physical embodiments of our invention and explained the operation and principle thereof, what we claiml as new and desire to protect by Letters Patent is: I

1. In a signaling system for railways, in

combination: a stretch of track divided into track circuit sections; a circuit controller; means rendered effective if a portion of the track is occupied by a train and another portion is not occupied for closing said circuit controller; means capable of acting initially only when said first means is effective for maintaining said first means effective so long as said other portion of the track is occupied; a circuit including said circuit controller; means for interrupting said circuit while said first mentioned portion of the track is occupied; and means for signaling controlled by said circuit.

2. In a signaling system for railways, in combination: a first track circuit section and a second track circuit section; a device adapted to be governed electrically; a circuit for rendering said device effective controlled jointly by both of said track circuit sections and closed if the first track section but not the second track section is occupied by a train; another circuit controlled jointly by said device and said first track circuit section, and closed if said device is effective and said first track section is unoccupied; means rendered capable of acting initially only when said device isefiective for maintaining I said device effective while said second track section is occupied; and means for signaling governed by said another circuit.

3. In a signaling system for railways, in combination: a track circuited track including a first track circuit section and a second said device including in series said circuit controller and said armature; a circuit having a normally open break therein closed by said device when it is energized; means for interrupting said last mentioned circuit while said first track section is occupied; and means for signaling governedby said last mentioned circuit.

4. In a signaling system for railways, in' combination: a track circuited track including a first'trackcircuit section and a second track circuit. section each having a track relay; an armature operated by the track relay of the first track section and closed when that track relay is dee'nergized; a circuit controller governed by the trackrelay of the second track section and opened when that track section is occupied; a device adapted to be goi'erned electrically; a circuit for rendering said device effective including in. series said armature and said circuit controller; means capable of acting initially only when said device iseffective for maintaining said device efi'ective while the second track circuit section is occupied; a circuit governed ointly by said device and the track relay of the first track section and closed only when said device is effective and the first track sectionis not occupied; and means for signaling governed by the last mentioned circuit.

5. In a signaling system for railways, in combination: a stretch of track divided into track circuit sections; a. first semaphore and a second semaphore each having a stop aspect and a proceed aspect and governing trafiic in the same direction, a circuit for controlling the first semaphore; means for interrupting said circuit when av predetermined portion of the track is occupied; a circuit controller subjected to the same controlling influence as the second semaphore and'closed' when that semaphore has its pro ceed aspect; another circuit controller govtrolling the controlling circuit for the first semaphore.

6. In a. signaling system for railways, in combination: a stretch of track divided into track circuit sections; a first semaphore and a second semaphore each having a stop aspect and a proceed aspect and governing traffic in the same direction, a circuit for controlling the first semaphore having its continuity determined at two separate places; means for breaking said circuit at one of said places when a portion of the track protected by the first semaphore is occupied; a translating device having cooperating contacts which maintain the continuity of said circuit at the other of said places avhen said translating device is en-- ergized; a circuit controller subjected to the same controlling influence -as the second semaphore and closed when that semaphore assumes its proceed aspect; another circuit controller governed by the first mentioned portion of the track and closed when that portion is occupied; a circuit for energizing said translating device including said circuit controllers in series; and means for maintaining the cooperating contacts of said device closed until the second semaphore indicates proceed, said last mentioned means beinginitially dependent on the cooperating contacts of said device being concurrently closed.

7, In a signaling system for railways, in combination: a stretch of track divided into track circuit sections; a first semaphore and a second semaphore for governing traffic in the same direction over said track; a circuit controller subjected to the same controlling influence as the second semaphore and closed when that semaphore indicates that a predeterminedportion of the track protected by the first semaphorezand by said circuit controller for closing said circuit at the other of said places, and means initially dependent upon said first mentioned means being concurrently effective for maintaining said first mentioned means effective to close said circuit as long as said portion of track protected by said second semaphore is occupied.

8. In a signaling system for railways, in combination: a stretch of track circuited track; a first semaphore and a second semaphore for governing trafiic in the same direction over the track; a circuit for governing the first semaphore and for causing that semaphore to assume a. proceed aspect when that circuit is closed, said circuit having two places at which itmay be broken; means governed by a predetermined portion of the track protected by the first semaphore for interrupting said circuit at one of said places when that portion of the track is occupied; a translating device which, when energized, establishes the continuity of said circuit at the other of said places; a circuit controller subjected to the same controlling influence as the second semaphore and closed when that semaphore indicates that the portion of track protected thereby is not occupied; another circuit controller governed by the first mentioned predetermined portion of the track and closed when that portion is occupied: a preliminary energizing circuit for said translating device including both of said circuit controllers in series; a maintaining circuit, including a source of current, for maintaining said translating device energized and efi'ective only when said energizing circuit is closed at the time said maintaining circuit is closed; and means for keeping said maintaining circuitclosed while the portion of track protected by the second semapl'iore is occupied.

9. In a signaling system for railways, in combination a stretch of track divided into track circuit sections; a sema 'ihore having a proceed position and a stop position; a circuit controller governed by the semaphore and closed when said semaphore assumes its proceed position; a second circuit controller gove 'ned by a predeternlined portion of the track and closed when that portion is occupied; a device adapted to be governed electrically; a circuit for energizing said device including in series said circuit controllers; a circuit controlled by said device; means for interrupting said last mentioned circuit when said predetermined portion of the track is occupied; and means for signaling governed by said last mentioned circuit.

10. in a signaling system for railways, in combination: a stretch of track divided into track circuit sections: a semaphore having a proceed position and a stop position; a circuit controller governed by the semaphore and closed when said semaphore assumes its proceed position; a second circuit controller governed by a predetermined portion of the track and closed when that portion is occupied; a device adapted to be governed electrically; a circuit for rendering said device eti'ective including in series said circuit controllers; a circuit controlled by said device: means for interrupting said last mentioned circuit; when said predetermined portion of the trac is occupied; means for signaling governed aid last mentioned circuit; and means c: )lt oi acting initially only when said d ice is effec ve for maintaining said device etiective so tong as said semaphore rcmair in its stop position.

11. in a signaling for railways, in

combination: a stretch of track divided into track circuit. sections; two semaphores each having a proceed aspect and a stop aspect and governing traffic in the same direction over the track; a circuit for governing the first of said semaphores including two circuit controllers arranged in series, one of said circuit controllers being governed by a portion of the track protected by the first semaphore and being opened when that portion of the track is occupied; electrically operable means which, when energized, closes the other of said circuit controllers; a third circuit controller subjected to the same. controlling influence as the second semaphore and being closed when that second semaphore assumes its proceed aspect. and being opened when that semaphore assumes its stop aspect: a fourth circuit con troller governed by said portion of the track protected by said first semaphore and closed when that portion of the track is occupied; an energizing circuit for said electrically operable means including a source of current and said third circuit controller and said fourth circuit controller in series; and means for maintaining the circuit controller governed by said electrically operable means means closed as long as said second semaphore n'iaintains its stop aspect, said last mentioned means being initially dependent upon said electrically operable means being concurrently ett'ective.

12. In a signaling system for railways, in combination: a stretch of track divided into track circuit sections each having a track relay; a circuit; means controlled by the track relay of one of said track sections for interrupting said circuit; a ei'rcuit controller included in said circuit; means which. wLien supplied with current, closes said circuit c )ntroller; a circuit for supplying current to said means and having a normally open break and a normally closed break therein; an armature operated by the first mentioned track relay for closing the normally open break when that track relay is deenergized; and means controlled by the track relay of another track circuit section for opening said normally closed break when that track section is occupied.

13, In a signaling system for railways. in combimition; a stretch of track including two track circuited portions; a semaphore for governing tratlic over the track; a circuit for controlling said semaphore having its continuity determined at two places therein; means controlled by a portion of the track protected by said sen'iaphore t'or interrupting said circuit at one of said places when that portion of the track is or cupi'ed; another semaphore for governing traliic in the same direction as the first sen) aphore; a circuit controller subjected to the same controlling influence as said other seniiiitl aphore and closed when that other semaphore indicates that a portion of the track traffic governed thereby for closing said first mentioned circuit at the other of said places and for maintaining said first mentioned circuit closed at said place until the train has left the portion of track protected by said other semaphore. v

14. In a signaling system for railways, in combination: a. stretch of track including two separate track circuited portions; a semaphore for governing trafiic over the track; a circuit for controlling the semaphore to cause it to assume its proceed aspect when energized; means controlled by a portion of the track protected by the semaphore for interrupting said circuit; electrically operable means which, when ineftective, opens another break in said circuit;- means for rendering said electrically operable means effective; a second semaphore for governing traffic in the same direction as the first semaphore; means controlled by said second semaphore and rendered effective when that semaphore assumes its stop aspect for preventing the energization of said electrically operable means; and means initially dependent upon said electric-ally operable means being concurrently effective for maintaining that means eifective while said second semaphore has its stop aspect.

15. In a signaling system for railways, in combination: a stretch of track divided into track circuit sections and including two contiguous portions; a circuit; means governed by one of said portions of the track for interrupting said circuit when that portion is occupied; a translating device, which when energized, closes said circuit it it is not interrupted by said means; a circuit controller governed exclusively by the first mentioned portion of the track and closed when that portion is occupied; a circuit controller governed by the other portion of the track and open when that portion is occupied; a circuit for energizing the translating device including in series both of said circuit controllers: and means for signaling controlled by said first mentioned circuit.

16. In a signaling system for railways in combination; a stretch of track divided into track circuit sections; a semaphore; a circuit for controlling said semaphore; means control-led by a track circuit section protected by the semaphore for interrupting said circuit when that track section is occupied; electrically operable means which, when rendered efiective, closes said circuit when the first mentioned means does not in- 'terrupt said circuit; two circuit controllers; a circuit for rendering said electrically op- .long as said another erable means efi'ectiv including said two circuit controllers only; one of said circuit controllers being governed by said first mentioned track circuit section and being closed when that track circuit section is occupied the other of said circuit controllers being governed by another track circuit section and being open when the latter track circuit section is occupied; and means capable of acting initially only when said electrically operable means is effective for maintaining said electrically operable means effective so track circuit section is occupied.

17. In a signaling system for railways in combination: a stretch of track divided into track circuit sections and including two separate portions; a signal; a circuit for controlling said signal; means governed by one of said portions of the track for interrupt ing said circuit when that portion is occupied; a translating device which, when energized, closes said circuit if it is not interrupted by said means; a circuit controller governed exclusively by said first mentioned one of the portions of the track and closed whenthat portion is occupied; a second circuit controller governed by the other portion of the track and open when that portion of the track is occupied; and a circuit for energizing said translating device including in series both of said circuit controllers.

18. In a signaling system for railways, in combination: a stretch of track divided into track circuit sections and each having a track relay; a first circuit controller and asecond circuit controller actuated simultaneously by the tack relay of a predetermined track circuit section and opened and closed respectively when that track section is occupied; a signal; a circuit for controlling said signal including the first circuit controller and having a normally open break therein; a device adapted to be governed electrically and when energized closing said break in said circuit; an energizing circuit for said device including the second circuit controller; and means governed by the track relays of a portion of the track and initially dependent upon the previous and also concurrent completion of said energizing circuit for maintaining said device energized.

19. in a signaling system for railways in combination: a stretch of track divided into track circuit sections; a signal; a circuit for governing said signal; a circuit controller included in said circuit; electrically operable circuit and for closing said last-mentioned circuit simultaneously.

20. In a signal system for railways, in combination: a track divided into track circuit sections; a semaphore; two circuit controllers; a circuit for governing said semaphore including in series said two circuit controllers, one of said circuit controllers being governed by a predetermined portion of the track and'being open when that portion of the track is occupied by a train; a translating devicefor closing the other circuit controller when energized; another semaphore for governing trafiic in the same direction as the first semaphore and protecting-a portion of the track in advance of the first mentioned portion; a third circuit controller operatedby said another semaphore. said third circuit. controller being closed when said another semaphore indicates that the portion of track protected thereby is not occupied by a train, and being opened when said another semaphore indicates that said portion of the track is occupied; a fourth circuit controller governed by said first mentioned portion of the t 'ack and closed when that portion is occupied; an energizing circuit for said translating device including in series said third and said fourth circuit con- 'trollers only; a maintaining circuit includsaid second mentioned portion of the track is occupied.

:21. In a signal system for railways, in combination: a track.v divided into track circuit sections and each having a track relay; a first semaphore and a second semaphore for governing trafiic in the same direction over the track; two circuit controllers; a circuit for governing the first semaphore including in series both of said circuit controllers, one of said circuit controllers being actuated by the track relay of a predetermined track section and being opened when that track section is occupied; a translating device, which, when energized, closes the other circuit controllers; a third circuit controller operated by the second semaphore and closed when a portion of the track in advance of the first mentioned track section is not occupied and being opened when that portion is occupied; a fourth circuit controller actuated by the track relay of said predetermined track circuit andclosed when that track relay is denergized; an energizing circuit for said translating device including in series said third and said fourth circuit controllers; a maintaining circuit including a source of current for maintaining said translating device energized, which circuit is effective only in case said energizing circuit is closed at the time the maintaining circuit is closed; and a fifth circuit controller for controlling said maintaining circuit which is closed so long as the second mentiond port-ion of the track is occupied.

' WILMER V. SALMON.

FRANK L. DODGSON. 

